As a pressure sensor used for this sort of flow rate measuring mechanism or mass flow controller, as disclosed in Patent Literature 1, there is known a sensor that receives pressure of fluid with a pressure sensitive surface provided on a diaphragm or the like, and, on the basis of a displacement of the pressure sensitive surface, measures a value of the fluid pressure. In the pressure sensor based on such a system, as an area of the pressure sensitive surface in a pressure receiving member is increased, sensitivity is improved.
Meanwhile, conventional mass flow controllers include one having a configuration in which a pressure sensor, a flow rate control valve, and the like are attached to a body inside which a flow path through which fluid to be controlled flows is formed. In particular, in recent years, at the request of compactly arranging a plurality of mass flow controllers in parallel, or other request, as illustrated in FIG. 10, there has been developed a mass flow controller 100′ of which a body 1′ is formed in an elongated shape, and a component attachment surface 1c′ set for one surface parallel to a length direction of the body 1′ is attached with pressure sensors 2′, flow rate control valve 4′, and the like in series along the length direction to thereby keep a width direction size of the whole of the mass flow controller small.